Pachyceras is a genus of perisphinctoid ammonites from the Middle Jurassic, upper Callovian stage, and is the type genus for the family Pachyceratidae. The shell is involute, subglobular, with a deep umbilicus and flattened flanks that slope toward a more narrowly rounded venter, and covered by low, widely spaced ribs.
Distribution Jurassic deposits of Egypt, France, India, Saudi Arabia and Switzerland.Paleobiology Database - Pachyceras. 2017-10-18.
References
D. T. Donovan, J. H. Callomon and M. K. Howarth 1981. Classification of the Jurassic Ammonitina; The Ammonoidea. The Systematics Association special volume no. 18